noun
: an eyepiece (as of a telescope) equipped with a prism or mirror to interchange opposite sides of the field and give a mirror image — compare reversing prism
noun
: an eyepiece (as of a telescope) equipped with a prism or mirror to interchange opposite sides of the field and give a mirror image — compare reversing prism
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012